A conventional image forming apparatus includes a fusing unit, which fuses a latent image onto a document. The fusing unit typically includes a heat roller, a fusing roller, a fusing belt stretched across the heat roller and the fusing roller, and a press roller proximate to either the heat roller or the fusing roller. The latent image is fused on the document when it passes between the press roller and the fusing belt on either the heat roller or the fusing roller.
The fusing belt rotates by rotation of the heat and fusing rollers. This fusing belt rotation results in a sliding force that may move the fusing belt away from its central position on the rollers towards the edge of the rollers. This sliding can result in improper fusion of the latent image to the document.
To avoid this sliding, a regulating part is placed on an edge of the rollers. In the conventional image forming apparatus, the regulating part is place over an edge portion of the roller and is fixed to a wall or other fixed (non-moving) portion of the image forming apparatus. FIG. 1 shows a portion of a fusing unit in an image forming apparatus including a conventional regulating part. As shown in FIG. 1, the fusing unit includes a roller 1, a fusing belt 2, a regulating part 3, and a fixed portion 4. The regulating part 3 is coupled to the fixed portion 4 by a fixing element 5, such as a screw. The fixed portion 4 is also coupled to a bridge portion 6 positioned at the end of the roller 1 to enable roller 1 to rotate.
Although the regulating part 3 counteracts the sliding force and maintains the fusing belt 2 in its proper position on roller 1, the conventional design of FIG. 1 results in other drawbacks. With the fixed regulating part 3, the fusing belt 2 contacts the regulating part 3 when the roller 1 rotates, generating a friction force between the moving fusing belt 2 and the fixed regulating part 3. The generated friction force damages the fusing belt 2, requiring replacement of the fusing belt, which increases the costs for operating the image forming apparatus, and increases the down time of the image forming apparatus.
In addition, the image forming apparatus typically drives either the fusing roller or the heat roller with a motor, and the other roller is left free standing. This design results in a high tension force on one side of the fusing belt 2, i.e., the side being pulled toward the motorized roller. The high tension force causes the portion of the regulating part 3 on the side corresponding to the high tension force to be carved deeply. As a result, the regulating part needs to be replaced as well.
Accordingly, it would be desirable to have a regulating part which improves the operation of the fusing apparatus and the life cycle of the fusing belt.